Trois essais sur la région MENA et l'économie informelle. / Informality is a social and economical phenomenon that has huge implications on societies. Over $3.1 trillion annually is lost to tax evasion worldwide (see The Tax Justice Network report). Informality means different things to different people. Sometimes this term is used to describe tax evasion and sometimes to refer to noncompliance with labor or regulations. Whatever definition is used, informality can be a serious problem in some countries, stifling investment, undermining the overall competetiveness of the whole economy and impeding growth. It could also be an important remedy in other countries playing a role as a mechanism of economic adjustment and source of livelihood for the poor and unemployed. Hart [1973] was the first anthropologist to observe, study and coin the word "informal economy" in his research in Accra and today’s literature is largely based on his work. Societies started acknowledging the importance of informality and then eventually economists, sociologists and anthropologists started analyzing its characteristics worldwide. […]

Cette thèse étudie les fluctuations macroéconomiques égyptiennes et compare leurs sources avec celles de certains pays du Moyen-Orient et Afrique du Nord (MENA). Un large éventail de méthodes économétriques sont utilisées pour examiner la synchronisation entre les cycles classiques et de croissance égyptiens et ceux de la région MENA, et de quantifier leurs sources de fluctuations ainsi que leurs réponses à ces sources de chocs. Nous ne trouvons aucune preuve de la synchronisation entre les cycles égyptiens et ceux de la région MENA et des pays développés. Les sources des fluctuations égyptiennes sont presque également réparties entre les chocs internes et étrangers, et les chocs du prix du pétrole semblent être le principal moteur de fluctuations de la production. En outre, la capacité de l'économie à contenir l'impact domestique des chocs externes négatifs à travers les chocs domestiques de l'offre et la demande est positive. / This thesis studies Egyptian macroeconomic fluctuations and compares their sources to those of some Middle East and North African (MENA) countries. A wide range of econometric methods are used to investigate the synchronization among Egyptian and MENA classical and growth cycles, and to quantify their sources of fluctuations along with their responses to these sources of shocks. We find no evidence of synchronization between Egyptian cycles and those of MENA and of developed countries. The sources of Egyptian macroeconomic fluctuations are almost equally divided among domestic and foreign shocks, and oil prices shocks appear to be the main driver behind output fluctuations. Moreover, domestic supply and demand shocks play a positive role in moderating negative foreign shocks affecting the economy.